Dog-type lockout and position indicator assembly

ABSTRACT

A connector assembly for connecting two members that allows manual lockdown to prevent accidental disengagement. The connector assembly can be used to connect a tension ring to a housing on a riser by using a lower set of hydraulically actuated dogs. A set of upper hydraulically actuated dogs on the connector assembly can be used to connect the tension ring to a diverter housing mounted on a rig. The connector assembly also has position indicators that ride along with the dogs to indicate whether the dogs are in the engaged or disengaged position.

FIELD OF INVENTION

This invention relates in general to tension rings and in particular toa dog-type lockout assembly for a tension ring that has a manuallockdown feature and indicates the dog position.

BACKGROUND OF THE INVENTION

Locking mechanisms for oilfield equipment often include a cylindricallocking mechanism called a dog. The dog is put into a locking positionbetween two components, such as a tension ring and a housing, to hold aposition or take a load. For example, the dog can be part of a tensionring that can maintain a riser in stable tension when offshore platformsheave. When the riser is retrieved, the dog can be locked to a housinglocated on the riser to prevent it from falling and injuring personnel.An additional dog can lock onto another component for storage.

To prevent the accidental unlocking of the dogs, a manual lockout can beemployed to secure the dog in a locked position. When the lockout isengaged, the dog is locked in an engaged position. When the lockout isdisengaged, the dog is free to move between an engaged and a disengagedposition. However, the actual position of the dog is unknown. Forexample, when a lockout is disengaged, the dog may still be in theengaged position. This may cause problems for the operators.

A need exists for a technique to manually lockdown dogs and indicatewhether a dog is in a locked or unlocked position. The followingtechnique may solve these problems.

SUMMARY OF THE INVENTION

In an embodiment of the present technique, a dog-type lockout assemblyis provided that integrates a position indicator that can provide visualconfirmation as to whether the dog is in the engaged or disengagedposition. The dogs can be manually locked down in the engaged positionto prevent the dog from being accidentally disengaged. The dog-typelockout assembly allows two components, such as a tension ring and ahousing, to be locked together to thereby hold a position or take aload.

In the illustrated embodiment, the dog-type lockout assembly has atension ring. The tension ring can have eyelets disposedcircumferentially around its exterior and adapted to receive wires thatattach to the structure of a rig. The ring can be adapted to maintaintension on a drilling riser comprised of several thousand feet of pipeand extends from a rig down to the seafloor. The tension is applied tothe riser via the wires attached to the ring to thereby prevent theriser from collapsing. The tension ring can apply tension to the riserthrough a housing connected to a slip joint.

When retrieving the drilling riser, in this example, the reaction pointbetween the housing and the tension ring is removed and the tensionwires go slack, allowing the tension ring to fall. This can be verydangerous to personnel working on platforms below the tension ring. Toprevent the tension ring from falling during retrieval of the riser, adog is used with the tension ring to lock into a mating passage on thehousing. This prevents the tension ring from falling and allows the ringto be carried upwards to where another component can be mounted. Thecomponent can be, for example, a diverter support housing mounted on therig. Another set of dogs on the tension ring can engage with thediverter support housing when the tension ring contacts the divertersupport from below. The tension ring can be stored in this position.

A hazard can arise if the dogs are accidentally disengaged by actuatingthe dogs hydraulically. To prevent this hazard, a manual lockdown can beused to ensure the dog remains in the engaged position. The lockdown canbe a mechanically driven screw located behind the engaged dog. When thelockdown is retracted the dog can float into both engaged and disengagedpositions. When the lockdown is extended, the dog is only permitted tobe in an engaged position. The solution adds a floating ring andposition indicator rod to the dog that rides along with the dog to showthe position of the dog. The position indicator will visually appearrecessed within the ring body when the dog is in the engaged positionand will appear retracted from the ring body when the dog is in thedisengaged position. The floating ring can easily be radially positionedto make it easier to manufacture an assembly.

The dog-type lockout thus integrates position indication in oneassembly. The combination of features allowing manual lockdown of thedogs into an engaged position and providing visual confirmation as towhether the dogs are in an engaged or disengaged position,advantageously increase safety by preventing accidental disengagement ofthe dogs and providing a simple way to ascertain the position of thedogs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a tension ring in contact with a housingand lower dogs in the engaged position, in accordance with an embodimentof the invention;

FIG. 2 is an enlarged sectional view of the dog and position indicatorwithin a tensioner ring, in accordance with an embodiment of theinvention;

FIG. 3 is an enlarged sectional view of the dog and position indicatorwithin a tensioner ring with the lockdown member retracted, inaccordance with an embodiment of the invention;

FIG. 4 is a sectional view of a tension ring in contact with a diverterhousing and upper dogs in the locked position, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an embodiment of the invention shows a tensionerring or connector assembly 10 for connecting two members. One member canbe, for example, an outer member such as the riser tensioner ring 10itself and the other member can be, for example, an inner member such asa housing 11 on a slip joint 12 connected to a riser 14.

In this example, the connector assembly 10 can have eyelets 15 disposedcircumferentially around its exterior and adapted to receive wires 16that attach to a tension system that maintains constant tension. Thetensioner ring 10 can be adapted to maintain tension on a drilling riser14 comprised of several thousand feet of pipe that extends from a rigdown to the seafloor. The tension is applied to the riser 14 via thewires attached to the ring 10 to thereby prevent the riser 14 fromcollapsing. The tensioner ring 10 can apply tension to the riser 14through a housing 11 connected to a slip joint 12.

Referring to FIG. 2, the tensioner ring 10 can comprise a frame or body18 having at least one fluid cylinder or opening 19. An actuatorcomprising a lower dog 20 that is movable between an engaged positionand a disengaged position in a lower fluid cylinder 21 in response tofluid pressure. Lower dog 20 has an annular piston 21 that sealinglyengages opening 19. Hydraulic lines 22 can provide the fluid pressure tobe exerted on piston 21. The lower dog 20 has an interior end 24 thatextends through an interior opening 26 on the interior of the frame 18when the lower dog 20 is in the engaged position. In the engagedposition the lower dog 20 engages a mating hole or groove formed on thehousing 11. To indicate the position of the lower dog 20 a collar orfloating ring 28 connected to the lower dog 20, carries a lower positionindicator 30. In the illustrated embodiment, the lower positionindicator 30 is recessed within an aperture or opening 32 on the frame18 when the lower dog 20 is in the engaged position, thus providing avisual confirmation of dog's position. When the lower dog 20 is in thedisengaged position, the lower position indicator 30 will extend outfrom the aperture 32 in the illustrated embodiment. Position indicator30 is a rod that is parallel to an offset from an axis of opening 19.However, devices other than a rod may be used as a position indicatorfor the lower dog 20.

The openings 19 on the frame 18 can be covered by lower and upper caps56, 58. The lower cap 56 has a threaded opening 36. The aperture 32 forthe lower position indicator 30 can similarly be formed on the lower cap56. The upper cap 58 can likewise have a threaded opening 54 that allowsthe upper locking member 52 to pass through it. The aperture 50 for theupper position indicator 48 can similarly be formed on the upper cap 58.

A lower lockdown member or screw 34 extends through threaded opening 36of cap 56. In the illustrated embodiment, the lockdown member 34 isthreaded to enable it to move between retracted and extended positionsrelative to the cap 56. Screw 34 has a base that abuts the head of ascrew 37 attached to and forming part of lower dog 20. Extending thelower lockdown member 34 when the lower dog 20 is in the engagedposition causes the lockdown member 34 to lock the lower dog 20 in theengaged position to prevent the dog 20 from moving to the disengagedposition. The lower lockdown member 34 thus assures that the lower dog20 will remain engaged to the housing 11 as the riser 14 is retrieved.Conversely, the lower dog 20 is free to move between the engaged anddisengaged positions when the lower lockdown member 34 is in theretracted position.

Continuing to refer to FIG. 2, a similar locking mechanism can be usedto store the housing 11 after the riser 14 is retrieved. An upper dog 38can be located above the lower dog 20 and within the frame 18. The upperdog 38 has an annular piston 39 and slidingly moves between engaged anddisengaged positions in an upper fluid cylinder 39 in response to fluidpressure. Hydraulic lines 40 can provide the fluid pressure. The upperdog 38 has an interior end 42 that can extend through an interioropening 44 on the interior of the frame 18 when the upper dog 38, is inthe engaged position. In the engaged position the upper dog 38 engages amating hole or groove formed on a member such as a diverter housing 70(FIG. 3). To indicate the position of the upper dog 38 a collar orfloating ring 46 connected to the upper dog 38 carries an upper positionindicator 48. In the illustrated embodiment, the upper positionindicator 48 is recessed within an aperture or opening 50 on the frame18 when the upper dog 38 is in the locked position, thus providingvisual confirmation of the dog's position. When the upper dog 38 is inthe disengaged position, the upper position indicator 48 will extend outfrom the aperture 50 in this embodiment.

An upper lockdown member or screw 52 extends through a threaded opening54 in cap 58. Threads on rotary screw 52 enable it to move betweenretracted and extended positions relative to cap 58. Screw 52 has a basethat abuts the head of a screw 55 attached to and forming part of upperdog 38. Extending the upper lockdown member 52 when the upper dog 38 isin the engaged position causes the base of the lockdown member 52 toengage the upper dog 38 and prevents the dog from moving to thedisengaged position. The upper lockdown member 52 thus assures that theupper dog 38 will remain engaged to the diverter housing 70 (FIG. 3) toallow storage of the housing 11 within the diverter housing 70. Theupper dog 38 is free to move between the engaged and disengagedpositions when the upper lockdown member 52 is in the retracted positionas shown in FIG. 2.

The portion of the frame 18 that houses the upper dog 38 can be radiallyoffset outward farther than lower dog 20. This offset creates anincrementally larger inner diameter at the upper dog 38 portion of theframe 18 that facilitates engagement with the diverter housing 70.

While the invention has been shown in only one of its forms, it shouldbe apparent to those skilled in the art that it is not so limited but issusceptible to various changes without departing from the scope of theinvention.

1. A connector assembly for connecting two members, comprising: anactuator adapted to be carried by a first member, the actuator beingmovable in response to fluid pressure between a disengaged position andan engaged position with a second member; a frame mounted adjacent theactuator and having an opening; a lockdown member extending through theopening in the frame and being movable between retracted and extendedpositions, such that movement of the lockdown member to the extendedposition while the actuator member is in the engaged position causes thelockdown member to engage the actuator and prevent the actuator frommoving to the disengaged position, wherein the actuator is movablebetween the engaged and disengaged positions while the lockdown memberis in the retracted position; and a position indicator coupled to theactuator for movement therewith and protruding through an aperture inthe frame to indicate the position of the actuator.
 2. The assemblyaccording to claim 1, wherein the opening in the frame is threaded andthe lockdown member is threaded so that rotation moves it between theretracted and extended positions.
 3. The assembly according to claim 1:wherein the actuator moves along a longitudinal axis; the lockdownmember moves along the longitudinal axis; and the position indicator rodis offset and parallel to the longitudinal axis.
 4. The assemblyaccording to claim 1, wherein the actuator is located within a fluidcylinder and comprises: a piston reciprocally movable in the cylinder;and a dog connected to the piston for movement therewith.
 5. Theassembly according to claim 1, further comprising: a collar mounted tothe actuator; and wherein the position indicator is mounted to thecollar.
 6. The assembly according to claim 1, wherein the framecomprises a cap adapted to be secured to the outer member in alignmentwith and spaced from the actuator.
 7. A connector assembly forconnecting two tubular members, comprising: an outer member adapted tobe connected to one of the tubular members and having a central opening;an inner member that lands within the central opening, the inner memberadapted to be connected to the other of the tubular members; a pluralityof fluid cylinders on the outer member and spaced around the centralopening; an actuator carried within each of the fluid cylinders, each ofthe actuators having a dog on an inner end for engaging the inner memberand being movable in response to fluid pressure applied to the cylinderalong a cylinder axis between inner and outer positions; a lockdownmember mounted outward of each of the actuators, each lockdown memberbeing manually movable from a retracted position to an extendedposition, each lockdown member having an inner end that engages an outerend of one of the actuators while the actuator is in the inner positionand the lockdown member in its extended position, each of the actuatorsbeing freely movable in response to fluid pressure in the fluidcylinders while its lockdown member is in the retracted position; and aposition indicator coupled to each of the actuators for movementtherewith and extending alongside one of the lockdown members toindicate the position of each of the actuators.
 8. The assemblyaccording to claim 7, wherein the outer member has a frame portionlocated outward from each the actuators and containing a threaded holethat receives each of the lockdown members.
 9. The assembly according toclaim 7, wherein: each of the lockdown members is located on thecylinder axis of one of the fluid cylinders; and each of the positionindicators is located alongside and parallel with one of the cylinderaxes.
 10. The assembly according to claim 9, wherein the outer memberhas a frame portion located outward from each of the actuators, and eachof the position indicators protrudes through an aperture provided in theframe portion.
 11. The assembly according to claim 7, furthercomprising: a collar mounted to each of the actuators; and wherein eachof the position indicators is mounted to the collar alongside thecylinder axis.
 12. The assembly according to claim 7, wherein the outermember is a riser tensioner ring and the inner member is a housing onthe riser that lands in the ring.
 13. The assembly according to claim 7,wherein the fluid cylinders further comprise a set of upper fluidcylinders and a set of lower fluid cylinders.
 14. The assembly accordingto claim 7, wherein the outer member further comprises a set of eyeletsadapted for receiving a cable.
 15. The assembly according to claim 7,wherein frame caps are mounted to the outer member outward from eachfluid cylinder, each frame cap having a threaded hole for one of thelockdown members and an aperture for one of the position indicators. 16.A method of connecting first and second members, comprising: mounting tothe first member an actuator and a lockdown member; mounting a positionindicator rod to the actuator for movement therewith; aligning the firstand second members with each other; with fluid pressure, moving theactuator from a disengaged position to an engaged position in engagementwith the second member, the position indicator rod moving with theactuator to visually indicate the engaged position; then manually movingthe lockdown member from a retracted to an extended position intoengagement with the actuator, thereby preventing movement of theactuator from the engaged position.
 17. The method of claim 16, furthercomprising disconnecting the first and second members by: manuallymoving the lockdown member from the extended position back to theretracted position, after which the indicator rod will still visuallyindicate that the actuator is in the engaged position; then applyingfluid pressure to the actuator to move the actuator to the disengagedposition, the indicator rod moving along with the actuator to provide avisual indication that the actuator is in the disengaged position. 18.The method of claim 16, wherein: the step of mounting to the firstmember an actuator and a lockdown member comprises mounting the lockdownmember along a longitudinal axis of the actuator; and the step ofmounting a position indicator rod to the actuator comprises mounting theindicator rod alongside and parallel with the longitudinal axis.
 19. Themethod of claim 16, wherein the position indicator protrudes a selecteddistance through an aperture while the actuator is in the disengagedposition.
 20. The method of claim 16, wherein the step of manuallymoving the lockdown member from a retracted to an extended positioncomprises rotating the lockdown member.